Germanium diode



March 8, 1955 s. J. PowERs ETAL 2,703,856

` cmmiruu DIonE Filed June 3, 1955 FIG. 2.

4 INVENTORS I n. F BaN/VER 9/ 'By 54j. POWE' United States Patent O GERMANIUM DIODE Stephen J. Powers, East Orange, and Walter F. Bonner, Glen Ridge, N. I., nssignors to International Telephone This invention relates to the construction of a crystal contact device, such as a crystal diode, and particularly to the means for mounting the contact electrode within such a device. I

More specifically, my invention relates to a point contact crystal device comprising what is commonly known as a cat Whisker electrode, and a semiconductmg crystal element. .In devices of this type the mounting of the cat Whisker with respect to the crystal is very important, and a considerable amount of research and development has been made to find the most practical and eiiicient mounting means. The difficulty in obtaining a suitable mounting means becomes apparent when the various conditions which are imposed in the mounting means are considered. A few of these conditions are: the mounting means must not unduly lengthen or shorten the cat Whisker because the inductance of the device varies therewith, and is significant at the higher frequencies; the mounting means must maintain the required pressure between the cat Whisker and the crystal to obtain uniform conductivity of the device; the mounting means must restrict the area of the crystal within which the cat Whisker point is pressed so that the conductivity is maintainedA relatively constant.

Accordingly, it is an object of this invention to provide a crystal contact device which satisfies each of the above conditions, and which is simple and economical to manufacture.

It is a further object of my invention to provide a Aunique cat Whisker mounting means which permits the cat Whisker to be mounted Without imposing certain bends or curves on the cat Whisker, and further, effectively restricts the area Within which the cat Whisker may move before making contact With the crystal.

In accordance with an aspect of my invention, there is provided a crystal contact device comprising a semiconducting element and a contact member so that an end thereof is properly pressed against the semiconducting element. The means for mounting the contact member comprises a tubular member having an elongated .opening wherein a part of the contact member is positioned. The contact member is arced Within the tubular member to absorb any minor changes in pressure to which it is subjected. The area of the semiconducting member upon which the contact member is pressed, is restricted by the lateral dimension of the opening in the tubular member.

The above mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood, by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a cross-sectional view of one embodiment of the contact device;

Fig. 2 illustrates a preferred embodiment of my invention;

Figs. 3 and 3A are possible views taken along lines 3-3 of Fig. 1; and

Fig. 4 is still another embodiment of my inventiom Although, for the purpose of describing my invention, there is illustrated a crystal diode, it is to be realized that vthe principles of the invention may be applied in most types of contact devices.

Referring now to Fig. 1, there is shown a crystal diode comprising a hollow housing 1 made of an insulator material such as a ceramic or a plastic. Inside one end of the housing there is positioned irsemiconducting ele- 2,703,856 PatentedV Mar. 8, 1955 ICC bular support member 5. The tubular member 5 is preferably made from nickel or stainless steel and may be fastened by means of solder 6, to a second supporting member 7; the member 7 being made of the same ma terial as the supporting member 3. The device is hermetically sealed by Wax, plastic or other suitable sealing material 8. The ends of the supporting members 3 and 7, respectively, are reduced in cross-sectional area and extend a short distance out of the housing 1, serving as electrical terminals for the device.

In assemblying the device, the cat Whisker 4 is positioned in the tubular member 5 and the tubular member is preferably crimped towards one end thereof to properly retain the cat Whisker. The tubular member is then Welded or soldered at one end to the supporting member 7. The crystal 2 is positioned in the housing and the cat Whisker 4 is suitably pressed against the surface of the crystal 2 by pressure applied against the supporting member 7. The area on the crystal within Which the cat Whisker electrode may move before being pressed against the crystal is limited by the lateral dimension of the opening in the tubular member. This, of course, is highly desirable because it permits the reduction of the size of the crystal. The arc or bow formed in the cat Whisker offers suflicient resiliency to absorb minor changes in pressure to which it might be subjected.

The tube may be crimped in any suitable manner to secure the cat Whisker therein. The forms of crimping are illustrated in Figs. 3 and 3A.

Fig. 2 illustrates a second embodiment of the invention which offers certain advantages over the first embodiment. In particular, the open end of the tubular member 5 is reduced in diameter to further restrict the area within which the cat Whisker may move before being pressed against the crystal 2. Moreover, the supporting members 3 and 7 may be recessed, as shown, to accommodate the crystal 2 and tubular member 5, respectively. By recessing the supporting members, the soldering operation may be simplified by simply pouring the solder into the recessed portions before positioning the respective parts therein.

Still another embodiment of my invention is illustrated in Fig. 4. In this modification, instead of providing a hollow tubular member for supporting the cat Whisker, the necessary opening is provided by boring a hole 9 in the supporting member 7 The opening 9, of course, should be approximately the same dimensions as the opening in the tube 5. The neck portion 10 may be crimped against the cat Whisker, similarly as in the case of the hollow tube support.

It is important to recognize that in devices of this type, the inductanceand capacitance of the various parts become significant at very high frequencies. As pointed out above, the inductance of the device varies with the length of the cat Whisker at very high frequencies and it is apparent that the invention lends itself to permit changes in the length of the cat Whisker Without sacrificing the support of the cat Whisker. Moreover, the capacitance between the support members 3 and 7 respectively, becomes appreciable at very high frequencies and this may be simply adjusted, also without sacrificing the support of the cat Whisker. For example, the capacity between the support members may be increased by employing the modification illustrated by Figure 4, wherein the members 3 and 7 are spaced comparatively closer together.

By Way of example, a contact device Was designed having the following dimensions: the housing 1 Was .375 inch long, .187 inch outside diameter, .125 inch inside diameter, and made of unglazed non-porous ceramic. The supporting members 3 and 7 had a diameter of .125 inch, the smaller portions .046 inch, and made of lead plated steel. The crystal was germanium having dimensions of .050 x .050x .O20 inch and soldered to the sup-l devicewas sealed by a material known by its trade-mark name Araldite.

While I have described above the principles of my invention in connection withspecific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation of the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

l. A crystal contact device comprising a housing, a semiconducting element, an elongated conductive contact member, means supporting said semiconductng element and said contact member within said housing such that an end of said member is pressed against said semiconducting element, and means within said housing for limiting the area within which said contact member makes contact on said semiconductng element, characterized in that said last mentioned means comprises a member having an elongated opening therein, a part of said contact member lying within said opening and bearing against a wall thereof, the lateral dimensions of said opening defining said area within which said contact member makes contact to said semiconducting element.

2. The device according to claim l, wherein said member having an elongated opening is crimped against said contact member to further secure it thereby.

3. A crystal contact device comprising a housing, a semiconducting crystal element, a contact electrode, means supporting said crystal element within said housing at 30 one end thereof, an elongated tubular support for said electrode, the electrode lying partially therein and bearing against a wall thereof, means supporting said tubular support within said housing such that an end of said electrode is pressed against said crystal, said contact member bring arced to absorb minor changes in pressure to which it might be subjected.

4. The device according to claim 3, wherein said tubular support is 'crimped against said electrode to further secure it thereby.

5. The device according to claim 3 wherein said tubular support is cylindrically shaped and comprises an end portion of smaller diameter than the remaining p0rtion to further restrict the contacting area on said crystal.

6. A crystal contact device comprising a housing, a semiconducting crystal element, a contact electrode, means for supporting said crystal element and said contact electrode within said housing, such that an end of said electrode is pressed against said crystal, an elongated opening in said electrode supporting means, the electrode 1ying partially therein but arced against a wall thereof, whereby the contacting area on said crystal element is restricted by the lateral dimensions of said opening, and means securing said contact electrode within said electrode supporting means.

References Cited in the file of this patent UNITED STATES PATENTS 2,495,716 Girard Ian. 31, 1950 

1. A CRYSTAL CONTACT DEVICE COMPRISING A HOUSING, A SEMICONDUCTING ELEMENT, AN ELONGATED CONDUCTIVE CONTACT MEMBER, MEANS SUPPORTING SAID SEMICONDUCTING ELEMENT AND SAID CONTACT MEMBER WITHIN SAID HOUSING SUCH THAT AN END OF SAID MEMBEWR IS PRESSED AGAINST SAID SEMICONDUCTING ELEMENT, AND MEANS WITHIN SAID HOUSING FOR LIMITING THE AREA WITHIN WHICH SAID CONTACT MEMBER MAKES CONTACT ON SAID SEMICONDUCTING ELEMENT, CHARACTERIZED IN THAT SAID LAST MENTIONED MEANS COMPRISES A MEMBER HAVING AN ELONGATED OPENING THEREIN, A PART OF SAID CONTACT MEMBER LYING WITHIN SAID OPENING AND BEARING AGAINST A WALL THEREOF, THE LATERAL DIMENSIONS OF SAID OPENING DEFINING SAID AREA WITHIN WHICH SAID CONTACT MEMBER MAKES CONTACT TO SAID SEMICONDUCTING ELEMENT. 